The present invention relates to a method for the adsorption of oils floating on or suspended in water.
Because of the worldwide expansion of oil consumption, the seas are congested with oil-tankers carrying crude-oil. As a result, the possibility of contamination of water surfaces in harbors and even on the open seas by oils leaking from oil-tankers has been greatly increased. In addition, there is an increasing possibility that the industrial effluents from chemical plants and other plants using petroleum as the raw material will entrain various forms of oils and pollute nearby bodies of water. Furthermore, the growth of automobiles and expressways has reached the point where oils spilling from automobiles onto road surfaces are washed out by rainwater and carried off through sewage systems to pollute culverts, ditches, rivers and seas. Consequently, there has risen a necessity for means for efficiently removing oils floating on or suspended in waters of all sorts.
For this purpose, there have been proposed various kinds of oil-adsorbing materials. The oil-adsorbing materials available heretofore are broadly divided into two classes, one class using synthetic high-molecular subsances and the other class using natural fibers. Falling in the former class are those using polypropylene, polystyrene, polyurethane foam, etc. Those of the latter class use pulp fibers, coconut shell fibers, cotton fibers, peat fibers and straw.
Of the oil-adsorbing materials heretofore known to the art, those made of synthetic high-molecular substances generally have a fundamental defect that they lack in resistance to oils. They have another disadvantage that the materials, when disposed of by incineration in conjunction with adsorbed oils, give rise to molten polymers which will do damage to incinerators and issue noxious gases. In addition, the oil-adsorbing materials made of synthetic high-molecular substances have a fatal drawback that they fail to exhibit any adsorbing activity on the so-called chocolate mousse which is formed when the waste oil, rolled and pitched on waves, forms balls in consequence of the emulsification caused thereon by a small proportion of entrapped sea water. The oil-adsorbing materials made of synthetic high-molecular substances also have the disadvantage that they themselves may cause serious ecological problems if not thorough recovered after use on seas or oceans.
In contrast the oil-adsorbing materials using natural fibers have a disadvantage that, because of their high hydrophilicity, they exhibit a high water-adsorbing capacity. To be freed from this disadvantage, these materials must undergo a preliminary treatment designed to impart water repellency or waterproofness thereto. Owing to their generally high levels of specific gravity, they fail to remain afloat on water and tend to sink under water. They also suffer from the disadvantage that they have rather limited capacities for adsorbing and retaining oils.
An object of the present invention is to provide a method for the adsorption of oils, which method enables oils including chocolate mousses floating on or suspended in water to be effectively adsorbed.
Another object of this invention is to provide a method for the adsorption of oils, which method permits required adsorption of oils with an extremely high efficiency.